Phonographic apparatus



Feb. 25, 1936. L. T. SACHTLEBEN PHONOGRAPHIC APPARATUS Original Filed June l, 1933 Zilli/i0.

INVENTOR I BY l Q ATTORNEY satema re. 2s, 193e UNITED STATES PATENT OFFICE PHONOGRAPHIC APPARATUS Lawrence T. Sachtleben, Camden, N. J., assignol to Radio Corporation of America, a corporation of Delaware 4 Claims.

This invention relates to phonographic apparatus and more particularly, to the variety therefl used for recording sound upon a photographic This application is a division of my application Serial No. 673,863, led June 1, 1933, now matured into Patent No. 1,983,310.

It involves an improvement in sound recording apparatus wherein the light reflecting mirror is actuated directly by the diaphragm as disclosed in Fritts Patent 1,203,190 and relates more particularly to a number of improvements in the mirror actuating mechanism of such apparatus.

The particular apparatus herein described 'is especially adapted for use in a camera wherein the operator thereof records his descriptive discussion while taking the picture.

Recording is accomplished by vibrating a narrow line of light transversely of a portion of the film, and this vibration of the line of light is eff ected by the rotation or oscillation of a vibratable mirror about the axis of its support.

One object of the invention is to effect the axial rotation of the mirror by means of manually controlled adjustment for the purpose of obtaining a. zero setting thereof.

Another object of the invention is to provide means for retaining the mirror spindle in predetermined relation to the driving rod of the diaphragm.

Another object of the invention is 'to provide means for pre-focusing the optical system of the apparatus so that the recording units are interchangeable Without further adjustment.

Another object of the invention is to provide means for damping cantilever vibrations of the mirror carrying spindle.

Anotherv object of the invention is to provide means for retaining the driving spindle and mirror spindle in co-operative relation, which will have substantially no eiect upon the frequency characteristics of the apparatus.

In the drawing:

Figure 1 is a rear View of a mirror driving mechanism made in accordance with my invention.

Figure 2 is a sectional view along the middle of Fig. 1.

Figure 3 is an enlarged view corresponding to the middle portion of Fig. 1.

Figure 4 is an enlarged View showing a modification of the driving rod and mirror spindle connections.

Figure 5 shows the casing of the recording unit and the means for securing accurate adjustment thereof in relation to the film position,

Referring first to Figs. 1 and 2: A sound-box is provided enclosing the diaphragm I, which sound-box has a cover 2 `fitted with a mouthpiece 3, as Well as a. rearcover 4. Through the rear cover 4 extends the driving rod 5 which is connected to the diaphragm I and vibrated longitudinally thereby. Pivoted against the driving rod 5 is the mirror spindle 6, which is illustrated as a rod diamond-shaped in cross-section but may be of any other suitable form. Carried upon one extremity of the rod 5 is the mirror 'l from which light' is reiiected to the recording surface.

The other of the acute angles of the diamondshaped rod is pivoted against the supporting member 8 which forms a fixed pivot therefor.

It will be apparent that sound waves lmpinging upon the diaphragm will produce longitudinal movement of the rod 5 whichwill rotate or oscillate the mirror spindle 6 about its pivot in the supporting member 8, and thereby cause shifting of the beam of light which is reflected from the mirror. The optical system for focussing the beam of light upon the mirror and converging it into the form of a narrow line upon the lm, is no part of this invention and, so far as this invention is concerned, it is immaterial what form it may take although the general arrangement shown in Taylor Patent 1,847,636 is quite satisfactory. Its construction and arrangement will be readily understood by those skilled in the art.

The member 8 is supported upon the member 9 which in turn is adjustably supported upon the rear face 4 of the sound-box.

The member 9 is, as shown, of a T-shape with the ends of the cross-bar thereof fastened to the cover 4 by the screws I0. The middle of this portion is supported upon the case by the pin Il which is set into the member 4 and upon which the member 9 can be moved. The screws I0 bend the member 9 very slightly over the member Il upon which the member 9 is to be rotated by pressure applied at the extremity of the other leg thereof. This rotation is eifected by actuation of the screw l2 which is threaded into the member 4 and also into the member 9. As Will be seen from Fig. 2, the portion of this screw which is threaded into the member 4 is of relatively large diameter while the portion threaded into the member 9 is of similar diameter, and the pitches of the threads thereon are in correspondence with these diameters. Due to the differential action therebetween, a very flne adjustment of the position of the member 9 can be secured, when the member is held rigidly in such adjustment.

It will be apparent that movement of the `screw I2 will accomplish an appropriate movement of 'the member 3 and thereby effect rotation of the spindle 6 which in turn adjusts the position of the mirror 1.

The member 8, which is provided with notches for pivoting the spindle 5, is secured to the member 9 by the screws I3 which holds it firmly against the pins Il over which it is slightly flexed to prevent any independent vibration thereof. Since the pins Il are located in the middle of the member 8 and the screws I3 are located at the ends thereof, the member 8 can be rotated on the pins I 4 as a pivot for the purpose of securing proper alignment of the spindle 6, by loosening one of the screws I3 and tightening the other.

'I'here may be some tendency for the spindle 5 to vibrate laterally. Any such vibration may be prevented in the manner shown in Fig. 3 wherein a small arm I5 is attached to the T-bar 9 and extends outwardly therefrom past the spindle 6. A small pad of rubber I6 is secured to the arm l5 and rests lightly against the spindle 8. This block of rubber serves to damp out any cantilever vibrations of the spindle 6 while at the same time it does not interfere with the freedom thereof to rotate.

Fig. 4 shows a slight modification of the construction shown in Fig. 2. In this figure the driving rod 5 is maintained rmly against the' spindle 6, and this spindle is in turn maintained securely against the member 8, by the action of a spring I1. This spring I1 is secured to a pin I8 in the member 9 and the end of the spring extends over a spacing block I9 on the member 8. This end of the spring is attached to the member 5 in the groove 23 as shown.

It will be apparent that the spring I1 maintains the elements 5, 5 and 8 in proper relation y to each other and, since the tension of the spring is transverse of the rod 5 and the material of the spring is quite flexible, it does not interfere with longitudinal vibration of the member 5.

It will be apparent that other types of. vibration-converting means other than the mirror 'I may be used if the construction is applied to other forms of apparatus, and the vibrationtranslating rod 5 may be of any cross-section v functionally equivalent to the diamond-shape shown although the diamond-shape is apparently\ the most convenient form providing two opposite knife-edges for engagement with the other members.

Referring now to the adjusting means shown in Fig. 5, the drum upon which the lm is carried past therecording point is indicated at 30. Thus drum is rotated upon a shaft 3i and coaxial with it is located a bushing 32 of predetermined diameter. This bushing is of annular form, and since the periphery thereof -is co-axial with the shaft 3i, it may be either merely slid over the said shaft and freely movable therewith, lor may be ixed against rotation by attachment to the plate 35. However, since the friction of this bushing 32 with the pin 31 would tend to impede the rotation of the shaft 3|, it is generally preferable to attach the bushingA to the frame 35. 'I'he mirpassing out of the casing 33 through an aperture in the plate 34.

The casing 33 is secured to a portion of the camera or recorder frame 35 by means of the screw 38 or as many similar screws as may be necessary or desirable, and these screws pass through elongated holes in the casing 33 so that a slight movement of the member 33 toward or away from the sprocket 33 is permitted. In the casing 33 is drilled a hole of appropriate diameter into 'which is tted a pin 31 which is 'secured in place by a screw 33. In manufacturing the device, the vcasing 33. when the optical system has been completely assembled, is placed in a Jig and shifted until the optical system is in correct focus. The pin 31 is then extended until it contacts with a stop member in the jig and is secured firmly in place by tightening the screw 38. By this means the end surface of the pin 31 is' maintained in uniform relation to the focal plane ofthe optical system.

If the bushing 32 is made of appropriate diameter, then when the unit 33 is inserted into the camera and brought to such a position that the pin 31 contacts with the bushing 32, the optical system will be accurately focussed vupon a film upon the sprocket 38.

It will be apparent that these recordingunits are not merely interchangeable with each other but can be exchanged between different recorders or cameras without refocussing.

The scope of this phase of the invention is not limited to directly actuated recording apparatus as, it will be apparent that a recording galvanometer or any equivalent apparatus which is pro- .vided with suitable members for abutment against and co-operation with the fixed members of the recording device may be substituted, and the camera or recorder canaccordingly be used interchangeably for various purposes, according to which type of device is included therein.

I claim: i

l. Phonographic apparatus comprising a drum adapted to support a nlm and to convey it past a recording or reproduction point, a unitary optical system adapted to focus a beam of light upon the said illm at the said recording or reproduction point, a bushing in concentric relation with the said drum.l and a member in predetermined'cooperative relation with the said optical system adapted to abut against the bushing whereby when said member and said bushing are in abutment, the optical system .will be focussed upon the said nlm.

2. Phonographic apparatus comprising a drum adapted to support a film and to convey it'past a recording or reproduction point, a unitary optical system adapted to focus a beam of light upon the said film at the said recording or reproduction point, a bushing in concentric relation with the said drum, and an adjustable member adapted to abut against the rst bushing and in predetermined co-operative relation with the said optical system, whereby when said members are in abutment, the optical system will be focussed upon the said lm.

3. Phonographic apparatus comprising a drum adapted to support a film an'd to convey it past a recording or reproduction point, a unitary oppoint, a fixed member in predetermined relation to the said drum, and an adjustable second member adapted to abut against the xed member and in predetermined co-operative relation with the said optical system whereby when said members are in abutment the optical system will be focussed upon the said lm.

LAWRENCE T. SACHTLEBEN. 

